EFFECT OF DEFECT PLACEMENT AND 

TAPER SETOUT ON LUMBER GRADE 

YIELDS WHEN SAWING HARDWOOD LOGS 

May 1961 

No. 2221 

UNITED STATES DEPARTMENT OF AGRICULTURE FOREST PRODUCTS LABORATORY 

FOREST SERVICE 

MADISON 5, WISCONSIN 

In Cooperation with the University of Wisconsin 
EFFECT OF DEFECT PLACEMENT AND TAPER SETOUT ON

LUMBER GRADE YIELDS WHEN SAWING HARDWOOD LOGS

By

F. B. MALCOLM, Technologist

Forest Products Laboratory,1 Forest Service

U. S. Department of Agriculture

Summary

The study here reported was made to evaluate some of the principles used by skilled sawyers as

well as some of the principles developed at the Forest Products Laboratory for getting the

optimum grade from all logs. The study, which was statistically designed, evaluates six sawing

methods for which the sawing faces were positioned relative to gross external defects and the

amount of setout for log taper. Lumber-grade yield tallies were summarized, and a quality

index was computed for individual logs, each grade, and each method. This index was calculated

from the value of the lumber sawn, based on prevailing market quotations. It was concluded

from the study that sawmill operators lose considerable money in producing their lumber by

ignoring the position of defects on sawing faces and taper setout.

Introduction

It is a recognized fact that the quality of hardwood timber in the United States has substantially

decreased in the past 50 years. This fact together with present day high production costs requires

that the hardwood sawyer must work carefully to develop the maximum value from logs which

reach the sawmill carriage. The sawyers’ problem is accentuated even further because high

quality veneer logs are often diverted to the veneer mill so that the quality of logs which do get

to the sawmill is much lower than those sawn in the mill of even 25 years ago.

To offset these conditions, skilled sawyers over the years have worked out their own methods of

placing, turning, and sawing logs on the sawmill carriage which they believe can develop the

maximum value from any given log. These methods may vary from region to region and from

area to area, partially because of the character of the market for end products but more often

because of a lack of study of the basic principles involved in obtaining the grade quality that may

be in a log. The beginning sawyer, who rarely has the advantage of being trained by a skilled

sawyer, must rely on his own trial and error methods or such written material as may be

available to him.

Written instructions on hardwood grade sawing were practically nonexistent until Telford's

instructions were published in 1951.2 These instructions were based almost entirely on

observations of sawing practices at many hardwood mills and from discussions with numerous

experienced sawyers.

2

Small Sawmill Improvement, C. J. Telford. U.S. Forest Products Laboratory Report No.

R899-27, 1951.

1Maintained at Madison, Wis., in cooperation with the University of Wisconsin.

Report No. 2221
The use of these instructions for demonstration training at sawmill clinics and subsequent

observations at numerous sawmilling operations indicated that while the instructions were

excellent for certain types of logs, they fell short of getting the optimum grade from all logs.

Experienced sawyers in certain areas, who had developed their own methods, had opinions of

their own which differed from the instructions. It was decided, consequently, to test the

instructions published by the Forest Products Laboratory against some of these variations in

grade-sawing procedures.

An initial pilot study, 3 which was statistically designed, was conducted on red oak logs in

cooperation with Professor J. W. Creighton, Michigan State University, on the University’s

sawmill at East Lansing, Mich. The study encompassed the following four sawing methods and

incorporated some degree of taper setout: (1) placing major log surface defects to the corners

or edges of sawing faces with a full taper setout, which is the FPL method modified; (2) placing

major log surface defects to the center of sawing faces and setting out only 1/2 taper, which is

an industry method and is sometimes called split taper; (3) placing the log hit-or-miss fashion

in which the defects as such were ignored, which is another industry method; and (4) placing

the major log surface defects to the corners or edges of sawing faces and setting out only 1/2

taper, which is another modification of the FPL method.

The analyses of variance of the compiled study data on grade No. 1 logs4 showed that the index

values for the corner-and-full-taper method and the corner-and-split-taper method were significantly higher than the index value for the hit-or-miss method at the 1 percent level. In the case

of grade No. 2 logs, the index values for the corner-and-full-taper, the corner-and-split-taper

method, and the hit-or-miss method were significantly higher than the value for the center-andsplit-taper method. In the case of grade No. 3 logs, the analysis showed no significant difference

between any of the methods.

The results of this pilot test were sufficiently encouraging to warrant more comprehensive

studies. In 1955, therefore, a study was initiated in cooperation with the Central States

Forest Experiment Station and its Carbondale Research Center.5 The study was conducted on

the Center’s sawmill at the Kaskaskia Experimental Forest in Illinois.

Although this study is concerned with a certain aspect of developing maximum grade value

from logs based on attention to external log defects, it is actually only a small part of the overall

problem of how to obtain maximum value from sawlogs.

Objectives

The basic objectives of this study were to determine the effect of varying the position of sawing

faces of a log in relation to the most prominent visible gross log surface defects and the effect

of taper setout on yields of factory grades of lumber when sawing hardwood logs. Knots, when

present, were considered as the log surface defects controlling the positioning of sawing faces.

In the absence of gross knots major log end defects, such as rot and holes, when present, were

the controlling surface defects. Over-growth, bark scars, and small visible end defects were

the controlling defects in the absence of other gross defects.

3An Evaluation of Defect Orientation Methods in Grade Sawing Northern Hardwoods, by

Creighton, J. W., Malcolm, F. B., and Wollin, A. C. Michigan State University

Agricultural Experiment Station Quarterly Bulletin 38: 216-224. November 1955.

4Hardwood Log Grades for Standard Lumber, Proposals and Results, "Forest Products

Laboratory Report No. D1737. "Hardwood Log Grades for Standard Lumber and How to

Apply Them." Report No. D1737-A, pocket edition.

5

The study was designed with the advice of D. O. Yandle, Laboratory statistician, C. L. Vaughan,

Laboratory log quality specialist, D. E. Herrick, Central States Forest Experiment Station

utilization specialist, and other members of the Station staff.

Report No. 2221 -2-
Scope

Although several of the most important hardwood lumber species will be tested eventually, only

species in the red oak group were tested in this study. This was done to eliminate the the effect

of the species variable in the analysis. For the same reason, only 4/4 lumber was sawed

except for the dog board. The hardwood lumber grade rules are identical for all the red oak

group. Logs used in the study were obtained from the Experimental Forest in the normal

logging operation for forest management studies.

Design

Because lumber quality yield was the criterion for evaluating each method tested, a uniform

distribution of logs of similar quality for each method was determined essential for a balanced

study. The FPL log grade specifications!! were used as a basis for obtaining the desired quality

distribution. Excessive sweep, however, was considered a variable that could obscure the

effect of orienting surface defects. Logs having sweep in excess of 10 percent as calculated by

the method indicated in FPL Report No. Dl737-A, therefore, were rejected for use in the study.

With this exception, only logs which met the FPL log grade specifications for factory grades

Nos. 1, 2, and 3 were used. An equal number of logs were selected as a means of obtaining

the desired distribution. Two different positions of sawing faces relative to the location of major

knot defects or other prominent defects on the sawing faces were used as the basic defectorientation factor; specifically, defects on the edges of the sawing faces, and, defects in the

center of the sawing faces. Two degrees of taper setout, one-half taper, and full taper, were

also considered essential factors to investigate. A control method was included in which defect

placement and compensation or adjustment for taper as such were ignored.

Equal effort was made in each sawing method to develop the best grade lumber from the standpoint of turning the logs and edging, ripping, and trimming the lumber for the highest value

return consistent with the minimum volume loss. Although maximum grade yield was the

controlling factor in edging and trimming, potential monetary value of individual boards was

equally considered so that scale was not sacrificed merely to up-grade. The optimum board

value was thus obtained.

The Michigan State University pilot study data were used as a basis for statistically determining

that 21 logs of each log grade for each sawing method were required for a balanced study. Five

methods combining the variants mentioned above and one control method were designed for

testing. 6

 There were, consequently, three grades of logs used for each of the six methods.

This required 378 logs, or 18 groups of 21 logs each.

Sawing Methods

The methods tested are described below:

Method 1. Control. Logs were sawed in the position they hit the carriage with defects and taper

being ignored.

Method 2. Logs were positioned so that major visible defects, such as knots, were oriented to

the center of the sawing faces and setout one-half the taper on the first of opposite unsawed faces.

The best face, which was determined by selecting the face with the longest cuttings and the

least number of defects, was sawed first. This determination was made from log diagrams.

6There are many other possible combinations of the three variables described above, but these

are the more common ones referred to as used by sawyers.

Report No. 2221 -3-
Method 3. Logs were positioned so that major visible defects, such as knots, were oriented to

the center of sawing faces and setout full taper. The best face was sawed first, and the taper

was removed from the lower grade heart portion.

Method 4. Logs were positioned so that major visible defects, such as knots, were oriented to

the edges of the sawing faces and not setout for taper. The poorest faces, which were determined

from log diagrams, were sawed first. This was a method developed at the Forest Products

Laboratory.

Method 5. Logs were positioned so that the major visible defects, such as knots, were oriented

to the edges of sawing faces and setout one-half the taper on the first of opposite unsawed faces.

The best faces were sawed first.

Method 6. Logs were positioned so that major visible defects, such as knots, were oriented

to the edges of the sawing faces and setout full taper. The best faces were sawed first, and the

taper was removed from the lower grade heart portion.

Field Procedure

The Kaskaskia Experimental Forest’s sawmill, on which the logs were sawn, is a conventional

circular mill that has a standard medium-weight 3-headblock carriage. The logs for the study

were obtained from various forest management compartments in which several types of forest

management research studies were being conducted. Logging and sawmilling operations are

intermittent because the crew also work at other jobs concerned with the operation of the Forest.

The sawing study was activated whenever a sufficient stock pile of logs had accumulated to

warrant operating 2 or 3 days and the crew was not required to work on other projects. The

number of Grade No. 1 logs that were necessary for the completion of the study accumulated

slowly because of the character of the timber types logged and the nature of the forest

management studies, These factors resulted in the study being spread over a considerable

period of time.

Diagraming and Grading Logs

All logs were given a number and diagramed before sawing in accordance with methods used for

the FPL log grade studies and graded in accordance with FPL log grade rules. The pattern of

sawing faces for each specific method was marked on both ends of the log before diagraming.

The diagram faces were developed to coincide with them. When the control logs were sawed,

of course, these diagramed faces were ignored.

Sawing the Logs and Recording Data

The sequence of sawing by methods was as listed previously, starting with Method 1 and

continuing through Method 6. Within a given log grade, a full group of 21 logs was sawed for each

method before progressing to the next method. Two or three extra logs were diagramed and

sawed for each grade and method in case of miscounting and misgrading. As each log was sawed,

individual boards were given a sequence number for that log. The position and sequence number

of each board sawed were diagramed with reference to the four sawing faces and the log diagram

faces on a circle diagram representing the end of the log. Each board was edged, ripped, and

trimmed so as to obtain the maximum grade value of the board consistent with the minimum

volume loss. This insured that the optimum monetary value of the board was obtained. A

separate tally of the scale, grade, and sequence number of every board was made for each log

by a hardwood lumber grader experienced in using National Hardwood Lumber Association rules.

Report No. 2221 -4-
Office Procedure

Computation, Tabulation, and Summarization

The total scale of each grade of lumber was determined for each log and the yield by individual

grades was reduced by 5 percent so as to allow for shrinkage. This placed the final tally on a

dry lumber basis, which is in accordance with practices established by the Forest Products

Laboratory for hardwood log grade studies. The total dry lumber footage for each log was thus

obtained. A quality index value was computed for each log using the method reported in the

Tennessee Valley Authority Technical Note No. 15.7 Grade yield percentages also were computed.

As field data of each sawing method for log grades Nos. 2 and 3 were completed, rough

preliminary summaries of grade yield percentage for each log were computed. When all the

grade No. 2 and 3 logs for all methods were sawed, the quality indexes for the individual log

grade were also computed.7 An analysis of variance was run on these data using the quality

index values thus obtained. Values obtained were in line with the final results. None of the data,

however, showed significance at the 1 percent level. Some of the data showed significance at the

5 percent level, although a major portion of the data approached significance at this significance

level.

Subsequent to making this analysis, a conference was held with the personnel from the Carbondale

Research Center, and it was decided to use current market values rather than a quality index

system for analyzing the overall study. Monetary values, consequently, were computed for

each individual log as well as the monetary value per thousand board feet for each log. These data,

as well as lumber grade yield data, log diameters, length, log and lumber scale, log grade,

and sawing method, for each log were punched on IBM. The values used for computing log and

lumber values were based on January 1958 Memphis Market Report for red oak as follows:

FAS, $190; Sel., $175; No. 1C, $90; No. 2C, $60; No. 3AC, $50; and No. 3BC, $26.

When the field work was completed for all grade No. 1 logs in all methods, a review and recheck

was made of field data for all grades and methods and of computations.

Results

Summary of Grade Yields, Monetary Values,

and Statistical Analysis Data

Tables 1 to 3 contain summaries of the comparisons of sawing methods by grade yields and

monetary values, based on the computed summaries of the field data in accordance with the

procedure as previously outlined. In order to simplify comparisons, the grade yield percentages

for each sawing method have been rounded to the nearest whole number.

Tables 4 to 9 contain summaries of the statistical analysis computations made to test the validity

of the data obtained from the study.

Discussion of Results

In each method used in the study, including the control method, every effort was made to continue

to turn every log and to edge, rip, and trim all boards so as to get the maximum grade in the

log consistent with optimum monetary value as related to volume loss in terms of board scale.

7Lumber Price Ratios for Computing Quality Index of Tennessee Valley Hardwoods, Technical

Note No. 15, Tennessee Valley Authority, Division of Forestry Relations, Norris, Tenn.

Report No. 2221 -5-
Table 1 is the overall comparison of methods in which the data for all grades of logs for each

method are combined. These data were treated statistically for variance to test the validity of

the spread of log values between log grades and to test the validity of the spread of value

between methods. The lumber value per thousand board feet was the index used in this analysis.

Table 5 gives the results of the treatment.

As would be expected from the design of the log grades themselves, the log-grade value

differences were highly significant at the 1 percent level. Of more importance, as far as

the study is concerned, however, is the test showed that value differences between methods were

highly significant and that these differences were not due to chance alone but to certain variables

within the individual method.

The next step was to determine which methods, if any, had a significant difference from the

others statistically. Tables 6 to 9 give the results of the statistical treatment for all log grades

combined and for individual log grades.

Lumber Values. --It is evident from table 1 that Methods 3, 4, and 6 return the highest lumber

value when sawing for grade. When analyzed statistically for a comparison of methods, the

data in table 6 shows that the value differences between Methods 1 and 2 and Methods 4 and 6 are

significant at the 1 percent level, and that there is a significant difference at the 5 percent level

between Method 2 and Methods 3 and 5.

There are several possible ways of interpreting these data. It seems logical to assume that

since the controlled variable of orienting defects to the edges of sawing faces is common to

both Methods 4 and 6, this factor has a strong influence on developing the highest value when

sawing for grade. It could be further assumed that since Methods 3 and 6 have a controlled

variable of full-taper setout common to them, this factor, likewise, has a strong influence on

developing the highest value when grade sawing. If this premise is accepted, then conversely,

using the same order of reasoning, the other controlled variable for Method 3, orienting defects

to the center of sawing faces, can have little influence on developing optimum lumber values. it

can also be assumed, then, that the controlled variable 1/2-taper setout, which is common to

Methods 2 and 5, likewise, has little effect in developing the highest lumber values in grade

sawing. This premise is deduced from the fact that Method 5 has the controlled variable of

defects oriented to the edges of sawing faces; this variable is common to Methods 4 and 6, and

appears to be one of the factors that strongly influences development of higher values in these

methods. It is logical, consequently, to assume that failure to take full advantage of developing

full-length boards from the outer one-third portion of the log, which generally has fewer knots

and other defects than the heart portion, has considerable influence on lowering the lumber values

in Method 5.

The results from Method 4 also tend to support the assumption that full taper setout helps develop

higher values when grade sawing. When poor quality faces are sawed first without taper setout

as in Method 4, the opposite higher quality sawing faces of logs, in effect, are sawed to the

equivalent of full taper setout. In this case, the higher quality faces automatically have become

parallel to the sawline and there is no need to setout for taper. This will enable the development of all full length boards from the higher quality faces. Logs with several knots on the

poorer faces, consequently, can be expected to develop values somewhat comparable to Method

6. This fact was taken into consideration in the development of the hardwood grade-sawing

guide, "Simplified Method for Developing Grade Lumber from Hardwood Logs," Forest Products

Laboratory Report No. 2056.

In considering the results from individual log grades (tables 3 and 4), it is not to be expected

that the same relative rating of value would develop for each of the three log grades as in the

overall summary. The study was designed for a uniform sample of quality for each method

rather than a uniform sample of quality within grades. Therefore, it is worth noting that some

of the data for the individual log grades did show significance in the statistical analysis of the

individual methods within grades (tables 7, 8, and 9), and that this significance was in the same

Report No. 2221 -6-
relative order as the significance shown in the data for the summary of the combined grades.

In addition, there appears to be a trend toward significance of the other values in the same order

of results.

Grade Yield Recovery. --Although the overall value of the product is the important consideration

to the sawmill operator, he is also vitally concerned with the proportion of the various grades

of lumber that are developed. He usually has little trouble in marketing his FAS and Select

grades. His problem frequently is in marketing his No. 3A and B Common grades, which he

often has to sell at a loss. It is logical to assume, therefore, that any method of reducing this

loss would be of value to him.

Visual inspection of the grade yield summary (table 1) shows that a sawmill operator using

Methods 4 or 6 can not only expect to obtain a much better yield of Selects and better, but also

expect some reduction in the amount of No. 3 Common lumber, particularly No. 3B Common.

In considering the grade yield by log grades, the results are even more noteworthy. It has been

observed that most sawyers will take particular care in sawing grade No. 1 logs. It might be

expected, consequently, that there would be only minor differences between methods for this

grade. In the yield of Selects and better from grade No. 1 logs (table 2), nevertheless, the

differences between the defect-controlled methods and the other methods are appreciable. In

grade No. 2 logs (table 3), these differences are even more pronounced. This grade, of course,

is characterized by logs having considerably greater number of defects8 than grade No. 1 logs;

such clear logs as may occur in this grade are of small diameter.

In grade No. 3 logs, defect orientation and taper setout appear to have an influence that should

not be ignored. Most sawyers, however, are prone to pay little attention to these logs, other

than to get them off the carriage as quickly as possible. They are, consequently, either "live

sawed" (through and through) or sawn into timbers. Although statistically the summary data for

this grade (table 9) are not significant, there is a definite trend toward significance indicating

that defect orientation and taper setout have a considerable influence on getting better value

from grade No. 3 logs.

Of particular importance in this regard is the reduction in the amount of No. 3 Common lumber

produced. It appears from these data that by ignoring defects in grade No. 3 logs, a sawyer is

producing 25 percent more No. 3 Common lumber than is necessary.

Overrun

Volume recovery was not a controlled factor of this study, because log diameters and lengths

were selected at random. The overrun figures for the study, nevertheless, are given to show

that there was no great difference in volume recovery in any one method, although the overrun

appears to be greatest for grade No. 3 logs in Methods 3 and 5, the 1/2-taper setout methods.

Since log diameters and length may have some effect on volume recovery, no specific conclusions

are warranted on overrun in this study.

Sawing Time

The character of the study did not permit making a sawing-time study. In view of this, a summary

of the number of saw lines and log turns was made from the board-sawing-sequence diagrams

for each log from each method. An analysis of the summary data did not indicate any appreciable

differences either between methods or log grades. The data simply indicated that the larger the

8

The clear cuttings for the most part are of smaller size in this grade than in log grade 1

because of the distribution of defects.

Report No. 2221 -7-
log, the greater the number of saw lines and turns. This was in line with what would be expected,

because the only basic difference between methods from the standpoint of actual sawing was the

placing of the log for the first sawing face.

Conclusions

The results of this study show sufficient trends to warrant the following broad conclusions:

1. When the relative position of defects on sawing faces is ignored, a loss results in potential

lumber quality for any given group of reasonably straight factory-grade red oak logs.

2. The placement of sawing faces of logs so that the major defects come to the edges of sawing

faces should result in higher quality lumber than when the sawing faces are placed with the major

defects in the centers of the faces.

3. When taper is ignored, a loss can result in potential lumber quality.

4. Full-taper setout has a greater potential for producing higher lumber quality than 1/2-taper

setout.

5. Lumber quality comparable to that obtained from sawing full-taper setout can be obtained

from similar logs having opposite low quality and high quality sawing faces if the low quality

faces are sawed first without setting out for taper. This has the effect of automatically putting

the high quality faces parallel to the saw line, which results in production of the maximum

number of full length boards from the high quality faces.

Additional Studies Indicated

This study does not contain the final answer for grade sawing. It is only a beginning of the

search to find out the best way to saw so as to develop optimum lumber value from any given type

and species of hardwood log. It was evident in reviewing the diagrams, data sheets, and the

sawing patterns for individual logs from this study that logs having certain characteristics could

possibly be sawed differently for better yield and that taper of the log within the same diameters

appears to influence grade recovery as well as volume recovery. It also appears that logs having

certain similar characteristics could possibly be grouped for a given sawing method. Logs having

certain combinations of good and poor faces might be sawed by one method, whereas logs having

unusual taper or having eliptical cross sections might be sawed by another. Sawing for combination of factory lumber and industrial stock, likewise, may require a modified method. Further

study also appears to be needed on the effect of diameter on grade recovery. The study did not

include logs with sweep in excess of 10 percent or logs with crook. These, too, may require a

different method of sawing to get the highest value lumber.

Report No. 2221 -8- 2.-l9
Table 1.--Comparison of sawing methods in terms of av

monetary values from all log grades combin
Table 2. --Comparison of sawing methods in terms of av

monetary values for Grade No. 1 logs
Table 3 .--Comparison of sawing methods in terms of average lumber gra

values for Grade No. 2 logs
Table 4 .--Comparison of sawing methods in terms of 

values for Grade No. 3 logs
Table 5 .--Analysis of variance comparing methods and

grades and their interaction

Report No. 2221
Table 6.--Comparison of sawing methods for all log grades combined

by their mean dollar value indexes using least

significant differences

Report No. 2221
Table 7.--Comparison of sawing methods for Grade No. 1 logs by

their mean dollar value indexes using least

significant differences

Report No. 2221
Table 8.--Comparison of sawing methods for Grade No. 2 logs by

their mean dollar value indexes using least

significant differences

Report No. 2221
Table 9. --Comparison of sawing methods for Grade No. 3 logs by

their mean dollar value indexes using least

significant differences

Report No. 2221